[augeas-devel] Calling augtool from a script

[Dominic Cleal]

On 23/04/13 18:24, Graham Leggett wrote:
> Hi all,
> 
> According to the FAQ entry at http://augeas.net/faq.html, the augtool command can be used to manipulate the tree from a script, but there doesn't seem to be a link to any documentation that would describe how to do this with working examples.
> 
> The closest I've found is the url http://stackoverflow.com/questions/9118123/using-sed-to-change-etc-fstab however trying to follow it's example I get augtool running silently with no error, but not doing anything to the file /etc/fstab:
> 
> augtool set '/files/etc/fstab/[file=/home/monica/foo]/file' /home/monica/foo
> augtool set '/files/etc/fstab/[file=/home/monica/foo]/spec' /dev/vg001/home-monica-foo
> augtool save

You're missing a "*" here which helps you find any node under fstab with
the given "file" subnode, plus the file values should be quoted:

set /files/etc/fstab/*[file="/home/monica/foo"]/spec
/dev/vg001/home-monica-foo

> Does anyone know how to get some kind of diagnostics or debugging out of augtool, to confirm that it is actually doing anything?

I'd suggest doing two things to narrow this down in future:

1. use "print" and "match" commands to check the path expressions you're
using find the right nodes, e.g.

augtool> print /files/etc/fstab/*[file="/home"]
/files/etc/fstab/3
/files/etc/fstab/3/spec =
"/dev/mapper/luks-10f63ee4-8296-434e-8de1-cde932e8a2e1"
etc...

whereas an incorrect path will simply return no output / matching nodes.

2. use "print" and "get" before and after setting values to see if it
worked:

augtool> get /files/etc/fstab/*[file="/home"]/spec
/files/etc/fstab/*[file="/home"]/spec =
/dev/mapper/luks-10f63ee4-8296-434e-8de1-cde932e8a2e1
augtool> set /files/etc/fstab/*[file="/home"]/spec /dev/sda3
augtool> get /files/etc/fstab/*[file="/home"]/spec
/files/etc/fstab/*[file="/home"]/spec = /dev/sda3

Regards,

-- 
Dominic Cleal
Red Hat Engineering